Off to new shores

The clouds hang over the Wadden Sea and the air smells of mussels and algae. In heavy rain, Christoph Evers trudges through the mudflats off the island of Norderney. The 33-year-old spatial planner negotiates tideways, which are now slowly draining as the tide recedes. There, in the sandy seabed off East Frisia, submarine cables will soon be laid to transport electricity from wind farms in the North Sea to the mainland.

Christoph Evers works for Amprion – and is one of the many new specialists the Dortmund-based transmission system operator has brought on board to help prepare for the next chapter of the energy transition: the expansion of offshore wind energy. In order for Germany to achieve its climate targets, the German government wants offshore wind farms to supply as much electricity as 20 large coal-fired power plants – and to do so by 2030. This requires not only the wind farms themselves, but also new cables connecting them to the onshore power grid. This is the only way the wind power generated offshore can reach the industrial centres in the west and south of Germany. Amprion will be investing billions of euros in this project. Christoph Evers is helping to plan these cables and to obtain the necessary permits. One of his areas of responsibility are the mudflats between the isle of Norderney and the mainland.

Until recently, everything that has been planned in this area and on the high seas was uncharted territory for Amprion. “Until now, we have planned, built and operated our transmission grid exclusively on land; that is, onshore,” says Evers, pointing towards the mainland. “Now, Amprion is going offshore for the first time.” The 33-year-old points towards Norderney. The offshore wind farms that Amprion is to connect to the grid will be erected up to 130 kilometres out to sea, behind the island. These links are expected to go online in 2028 and 2029. With a capacity of 900 megawatts each, they could cover the electricity needs of a major city such as Hamburg.

What animals and plants live on the mudflats?

The East Frisian Wadden Sea is part of the Lower Saxony Wadden Sea National Park – which in turn is part of the UNESCO World Natural Heritage Site that also covers the Schleswig-Holstein Wadden Sea and the Dutch Wadden Sea. Anyone planning to build a power line there must submit a comprehensive study depicting how the project will affect nature and the landscape. To this end, the flora and fauna along the planned corridor must be documented. These tasks are carried out on behalf of Amprion by experts such as marine biologist Dr Jens Stecher. Christoph Evers is accompanying him on this rainy October day. Stecher knows every tideway and sandbank in the mudflats off Norderney. And he knows the dangers: “When the tide comes in, the tideways can become torrents and cut off the way back to dry land,” says the 57-year-old scientist. To be on the safe side, the men wear life jackets and backpacks with provisions.

An hour after they have set off from the dyke near Hilgenriedersiel, they reach the first of a total of 18 waypoints. Stecher begins mapping biotope types on a large muddy area. For this purpose, he uses a light-alloy measuring frame, which he has carried in his hand the whole time and which is divided into open squares. He places it on the mudflat floor at previously determined points. He takes notes and photos of everything that can be seen inside the squares. The images will be evaluated later on the computer. Among other things, these observations can be used to deduce how heavily populated the tidal flats are at the respective location. “Every little lugworm cast counts,” says the marine biologist. Amprion can plan the course of the cable route accordingly.

Mudflats with an eventful history

While Christoph Evers is trudging around the mudflats, his colleague Michael Hahn is 300 kilometres to the south at Amprion’s head office in Dortmund, on the phone to companies that specialise in laying submarine cable in the tidal flats and coastal waters. The 34-year-old experienced mechanical engineer is one of many offshore experts Amprion has hired in recent months. He will have a say in deciding through which cables the electricity generated by the offshore wind farms will flow. This task is challenging. For Hahn needs to know what the seabed is like. “Only then can I tell you how to lay the submarine cable.” Geological studies using echo sounders show that sand, stones and gravel have been compressed into the seabed, and even peaty layers. They have evolved from former moors – and bear witness to the region’s eventful history: “Where the North Sea is today was land 10,000 years ago,” says Hahn.

To lay subsea cables, specialist companies use, among other things, underwater ploughs and special flushing methods. How do they impact the seabed? “With sandy seabeds, six months later it’s impossible to see any difference compared with the original seabed. That’s my experience from numerous projects I have been involved in,” says Hahn. Treating nature with respect is important to him. He grew up in Neuharlingersiel, 30 kilometres from the point where the new power line is to reach land. “That’s another reason why I want to leave nature there the way I found it.”

This is also important to Christoph Evers, who, ­after four hours on the mudflats, has reached the car park near the dyke again. He peels off his wet jacket and puts on dry clothes, then says goodbye to Jens Stecher. The mudflats through which they were tramping just a moment ago are being slowly submerged by the tide again. Soon, the water will have reached the salt marshes by the dyke – and will also have washed away the last traces of their hike.